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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
931

Glitch Reduction and CAD Algorithm Noise in FPGAs

Shum, Warren 20 December 2011 (has links)
This thesis presents two contributions to the FPGA CAD domain. First, a study of glitch power in a commercial FPGA is presented, showing that glitch power in FPGAs is significant. A CAD algorithm is presented that reduces glitch power at the post-routing stage by taking advantage of don't-cares in the logic functions of the circuit. This method comes at no cost to area or performance. The second contribution of this thesis is a study of FPGA CAD algorithm noise {random choices which can have an unpredictable effect on the circuit as a whole. An analysis of noise in the logic synthesis, technology mapping, and placement stages is presented. A series of early performance and power metrics is proposed, in an effort to find the best circuit implementation in the noise space.
932

Glitch Reduction and CAD Algorithm Noise in FPGAs

Shum, Warren 20 December 2011 (has links)
This thesis presents two contributions to the FPGA CAD domain. First, a study of glitch power in a commercial FPGA is presented, showing that glitch power in FPGAs is significant. A CAD algorithm is presented that reduces glitch power at the post-routing stage by taking advantage of don't-cares in the logic functions of the circuit. This method comes at no cost to area or performance. The second contribution of this thesis is a study of FPGA CAD algorithm noise {random choices which can have an unpredictable effect on the circuit as a whole. An analysis of noise in the logic synthesis, technology mapping, and placement stages is presented. A series of early performance and power metrics is proposed, in an effort to find the best circuit implementation in the noise space.
933

Modeling 1/f noise in a-Si:H field-effect transistors

Xu, Yang 17 October 2008
Hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) are used as switching elements in large area active matrix liquid crystal displays and various image sensing devices for radiation detection. The noise inherent in the a-Si:H TFTs contributes to the overall noise figure of such devices and degrades the signal to noise ratio; therefore, the noise is an important factor in the design of the devices. The noise of the a-Si:H TFTs has been studied experimentally, but the origin of the noise is not understood. <p> This work calculates the noise of the a-Si:H TFTs based on a simulation of operation of the TFTs and the hypothesis that the device noise is due to the intrinsic noise of the a-Si:H material. An a-Si:H TFT with an inverted-staggered structure has been simulated by numerically solving the fundamental transport equations for various gate and drain-source voltages. The drain-source curves derived from the simulation agree qualitatively with the experimental results: both the linear and saturated regions are observed. The low frequency noise was calculated based on the charge density distribution in the channel obtained from the simulation and the known dependence of the noise in the a-Si:H on the charge density, Hooges relation. The calculated noise power increases with the drain-source voltage and is inversely proportional to the gate voltage or the effective channel length. The curves agree qualitatively with the experimental results. The calculated noise power agrees quantitatively with the experiments when the scaling parameter in Hooges relation, , is set to . This value agrees with the experimentally determined value for a-Si:H. The results are consistent with the hypothesis that the low frequency noise in the a-Si:H TFTs is due to the material itself.
934

Formulation and implementation of a generic fleet-level noise methodology

Bernardo, Jose Enrique 08 April 2013 (has links)
The expected rise in aviation demand requires the reduction of the environmental impacts that impede this desired growth, such as fuel burn, emissions, and airport noise. A number of current technology programs attempt to identify, evaluate, and select the environmental technology solutions for the coming decades. Fleet-level evaluation will be essential to deciding between various technology options because it provides a system-level assessment that clarifies the effect of operational and policy variables. Fleet-level modeling in general, introduces various complexities, and detailed fleet-level models require significant time and computing resources to execute. With a large number of potential technology options available for assessment, a full detailed analysis of the technology space is infeasible. Therefore, a simplified fleet-level environmental evaluation methodology is required to select scenarios to carry forward for detailed modeling. Capabilities such as the Global and Regional Environmental Aviation Tradeoff (GREAT) tool, have achieved rapid simplified fleet-level analysis for fuel burn and emissions, but currently lack a satisfactory generic framework to evaluate fleet-level noise. The primary objective of this research is to formulate and implement a generic fleet-level noise methodology that allows decision makers to analyze the fleet-level impact of many technology scenarios on the quantity of noise, and also its distribution about certain airport types. This information can be leveraged to provide screening assessments of technology impacts earlier in the decision-making process, reserving more sophisticated modeling techniques for the most promising scenarios. The capability gaps identified are addressed by the development of a rapid generic fleet-level noise model that captures basic airport noise contour shape and contour area, a categorization of airports with respect to their operational and infrastructure characteristics, and the development of shape metrics that enable rapid classification and comparison of contour shapes. Once the capability gaps were addressed, the resultant System-Wide Assessment of Noise (SWAN) methodology was implemented via use cases to demonstrate the application of the methodology, examining the introduction of a set of possible near-term (N+1) future technologies into the forecast. While these examples are simplified and notional, they demonstrate the types of analyses and investigations that can be performed with the SWAN methodology, providing answers regarding the impact of technologies on contour shapes. The development, verification, validation, and demonstration of these capabilities complete a framework for evaluating fleet-level noise at the screening-level that retains the ability to capture and effectively discuss shape information beyond the capability of current screening-level noise evaluation techniques. By developing a rapid generic fleet-level noise model, a set of Generic Airports, and metrics that objectively quantify and describe shape, decision-makers can access greater levels of information, including the critical facet of contour shape in fleet-level airport noise.
935

QAM and PSK Modulation Schemes under Impulsive Noise

Pérez Rodenas, Ezequiel January 2012 (has links)
Nowadays most of the communications systems are designed considering only to work under AWGN (Additive White Gaussian Noise). But the implementation of wireless systems in industrial facilities brings different kind of interference from machines or any other kind of electronic devices. Some of them are sources of randomly and high power noise, which commonly is known as impulsive noise. The objective in this thesis is to study the impact of the impulsive noise on a communication using QAM (Quadrature Amplitude Modulation) and PSK (Phase-Shift Keying) schemes, by observing the BER (Bit Error Rate) and the APD (Amplitude Probability Distribution). For that, it is developed a measurement method that will be used in a real industrial environment in future work.      The content of this thesis is divided in two parts. In the first part is made a program in MATLAB to simulate the communication through a noisy channel. Then is developed a measurement method which is tested in three different ways corresponding to 3 different outputs of an spectrum analyzer, namely, 20,4 MHz IF output, video output and IQ data output.      The relation of impulsive noise is presented in the second part with different statistical properties in the BER and the APD, in the setup with the best performance. At the end of the thesis a concluding section summarizes the results obtained during the work and some lines of future work in a real industrial environment with the developed method.
936

Åtgärder för att minimera trafikbullers påverkan på ett rekreationsområde

Zingmark, Maria January 2010 (has links)
The aim of this inquiry was to investigate the most appropriate measures to reduce noise impacts from road traffic on the Nydala recreational area in Umeå municipality due to the planned re-routing of the E4 motorway to an existing road along this area. The sound environment is an important part in the experience when we are visiting recreational areas. Noise is not only disturbing; the liberty from unwanted sounds also allows us to perceive natural sounds that are a benefit for the cultural experience. Therefore it is important to take actions to protect this well used area from traffic noise. The reasonable options to avoid noise impact in this case are to lower the speed limit, using a noise reducing coating or use noise protection screens and walls. To estimate the measures suitability the starting points were to measure the effects on noise, the impact on the landscape, coasts and other possible side effects. It is important that the noise issue may not be replaced by other problems such as barrier effects, significant effects on the landscape or worsening living environment. To assess the reducing effect of the noise, calculations have been made. These showed that the measures that reduce noise spread were more favorable compared to those which prevent noise generation. The most appropriate measure in this case, based on the noise impact and influence on the landscape, is a 2 meter high acoustic screen in a combination of 0,5 meter wood and 1,5 meter tempered
937

Skalning och brusberäkning av tvåportsadaptorer / Scaling and noisecalculation of twoportadaptor

Samuelsson, Daniel January 2004 (has links)
The goal of this work is to summarize the calculations for scaling and noise of twoportadaptor. Two different methods has been described and used for the final results.
938

Transfer Cavity Stabilization Using the Pound-Drever-Hall Technique with Noise Cancellation

Torabifard, Mozhgan 24 January 2011 (has links)
A system for exciting Rubidium atoms to Rydberg states has been constructed to study the interactions between them and metal surfaces. This thesis describes a method to reach the f Rydberg series using diode lasers. Since the diode lasers need to be frequency stabilized for this excitation, a transfer cavity stabilization method was implemented using the Pound-Drever-Hall technique. To obtain the necessary frequency modulation the diode laser was current modulated at ∼ 6 MHz. A noise cancellation circuit was used to suppress detection of the accompanying residual intensity modulation.
939

Characterizing Noise in Quantum Systems

Magesan, Easwar 22 June 2012 (has links)
In practice, quantum systems are not completely isolated from their environment and the resulting system-environment interaction can lead to information leakage from the system. As a result, if a quantum system is to be used for storing or manipulating information, one would like to characterize these environmental noise effects. Such a characterization affords one the ability to design robust methods for preserving the information contained in the system. Unfortunately, completely characterizing the noise in a realistic amount of time is impossible for even moderately large systems. In this thesis we discuss methods and diagnostics for partially characterizing quantum noise processes that are especially useful in quantum information and computation. We present a randomized benchmarking protocol that provides a scalable method for determining important properties of the noise affecting the set of gates used on a quantum information processor. We also prove various properties of the quantum gate fidelity, which is a useful state-dependent measure of the distance between two quantum operations, and an important diagnostic of the noise affecting a quantum process. Some non-intuitive generic features of quantum operations acting on large-dimensional quantum systems are also presented.
940

Modeling 1/f noise in a-Si:H field-effect transistors

Xu, Yang 17 October 2008 (has links)
Hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) are used as switching elements in large area active matrix liquid crystal displays and various image sensing devices for radiation detection. The noise inherent in the a-Si:H TFTs contributes to the overall noise figure of such devices and degrades the signal to noise ratio; therefore, the noise is an important factor in the design of the devices. The noise of the a-Si:H TFTs has been studied experimentally, but the origin of the noise is not understood. <p> This work calculates the noise of the a-Si:H TFTs based on a simulation of operation of the TFTs and the hypothesis that the device noise is due to the intrinsic noise of the a-Si:H material. An a-Si:H TFT with an inverted-staggered structure has been simulated by numerically solving the fundamental transport equations for various gate and drain-source voltages. The drain-source curves derived from the simulation agree qualitatively with the experimental results: both the linear and saturated regions are observed. The low frequency noise was calculated based on the charge density distribution in the channel obtained from the simulation and the known dependence of the noise in the a-Si:H on the charge density, Hooges relation. The calculated noise power increases with the drain-source voltage and is inversely proportional to the gate voltage or the effective channel length. The curves agree qualitatively with the experimental results. The calculated noise power agrees quantitatively with the experiments when the scaling parameter in Hooges relation, , is set to . This value agrees with the experimentally determined value for a-Si:H. The results are consistent with the hypothesis that the low frequency noise in the a-Si:H TFTs is due to the material itself.

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